The present invention relates to an apparatus for fractionating suspensions including a tubular body having a centre and a circumferential strainer, and drive means arranged to turn the tubular body such that the strainer is turned at least intermittently about an axis extending through the centre of and substantially axially along the tubular body. Spray means is arranged to spray a suspension to be fractionated against the strainer such that a fine fraction of the suspension penetrates the strainer and a coarse fraction of the suspension is rejected by the strainer. Fine fraction discharge means is provided for discharging the fine fraction from the apparatus.
This type of spray fractionating apparatus is known to have a large flow capacity, compared with other conventional types of fractionating apparatus. However, a problem of the spray fractionating apparatus is that some of the coarse particles developed on the strainer can block the strainer holes and thereby prevent fine fraction from penetrating the strainer until said coarse particles have been removed from the strainer.